1. Field of Invention
This invention relates generally to portable chemical heaters for warming or cooking food, and more particularly to a heater of this type which uses diethylene glycol as a liquid fuel and which, despite its small size, is capable of generating heat for a prolonged period.
2. Status of Prior Art
In order to heat or warm food at a table or buffet, it is known to provide for this purpose a chafing dish or other food receptacle below which is placed a portable chemical heater.
The portable heater is usually of the STERNO type; that is, it takes the form of a can filled with an alcoholbased paste which when the exposed surface of the paste is ignited produces a flame of sufficient intensity to warm precooked food contained in the chafing dish or to cook food at a table or buffet.
One practical difficulty with known types of portable heaters of the STERNO type is that they have a short effective life that runs about a half hour. In practice, this period is often inadequate, particularly if the food is to be maintained in a warm condition for several hours.
Another drawback characteristic of known types of portable chemical heaters having fuel contained in a can is that the heat generated thereby is transferred to the can as well as to the chafing dish being heated; hence one not only experiences a loss of useful heat, but the heated can constitutes a hazard. Thus, if the user wishes to remove an exhausted can and replace it with a fresh can, he may be burned when grasping the exhausted can. Or if the user wishes, before the can is exhausted, to blow out the flame and put a lid on the can for subsequent use, in doing so he may be burned when handling the can.
Moreover, where the can is provided with a label of paper or other flammable material, the heat from the can may result in ignition of the paper, especially if the paper label is soiled by an ignitable cooking oil, as sometimes occurs. Yet another disadvantage of chemical heaters which use an alcohol-based paste is that they are smokey in operation and produce a disagreeable odor.